1. Field
The following description relates generally to wireless communications, and more particularly to retransmission of multimedia broadcast multicast services for a single frequency network (SFN), in a manner that maintains synchronized SFN transmission.
2. Background
Wireless communication systems have become prevalent in facilitating an emergence of worldwide communication utilizing portable, hand-held devices. Such devices have become smaller and more powerful in order to meet consumer needs, improve communication quality and clarity, and compete with traditional communication devices for providing multi-media services. An increase in processing power and network bandwidth has fueled such competition, but has also increased demand on wireless network operators and operator equipment.
One mechanism to facilitate high bandwidth communication for multi-media has been single frequency network (SFN) operation. Particularly, multimedia broadcast multicast services (MBMS) and MBMS for third generation partnership project (3GPP) long term evolution (LTE), also known as E-MBMS (including, e.g. what has recently come to be known as multicast/broadcast single frequency network MBSFN in the LTE context), can utilize such SFN operation. SFNs utilize radio transmitters, such as enhanced Node (eNode) base stations (Bs), to communicate with subscriber devices. Particularly, groups of eNode Bs can transmit bi-directional information in a tightly synchronized manner, so that signals reinforce one another rather than interfere with each other. As a result, competitive high bandwidth communication can be maintained for E-MBMS services.
On occasion, SFN data transmitted to one or more devices can be undecipherable, or simply lost. Such data must be retransmitted by a wireless network for a service to be maintained. Retransmission poses additional problems, however. For example, retransmission can take place over an entire SFN cell group, requiring every eNode B to retransmit the same block(s) of data. Coordinated retransmission consumes a large amount of bandwidth and a large amount of power. Additional problems occur as well, in that all eNode Bs have to determine which blocks are required by any device and what radio resources should be allocated to retransmission. Coordination among many eNode Bs consumes additional processing power as well. Consequently, wireless communication providers have conducted research into providing alternative mechanisms for retransmitting data.